What is the best way to prepare for a marathon?

Good performance in marathon events is achieved, above all, by the runner's capacity to maintain high levels of energy expenditure over a prolonged period of time. To achieve a good performance, a runner must make his body function at the highest level on D-Day. There are several complementary strategies for that: adaptations to training, rest and diet. It's essential to have a strategy for food during a marathon. It must not only satisfy the nutritional needs of the runner but also not be restricting or create any digestive pain.

Preparing for your marathon

During the preparation phase, you need to keep an eye on any changes in weight, which may require an adjustment in energy expenditure linked to the increase in training and daily calorie intake. A balanced diet facilitates energy management.

5 or 6 weeks before the marathon

Make sure that you have a strict balanced diet and a good healthy lifestyle.

  • Do not miss any meals and eat at regular times
  • Meat, fish, eggs: Once or twice per day
  • Starchy food: At each meal
  • Dairy products: 2 to 3 per day
  • Fruits and vegetables: At least 5 per day
  • Fat: vegetable fats are preferable in reduced quantities,
  • Sugar: limit consumption
  • Obviously, drink as much water as you can.

D-7: last week before the marathon

  • Increase carbohydrate intake to increase energy reserves
  • Drink as many fluids as possible
  • Limit fatty meat

D-3 and D-2: last few days before the marathon

  • Increase carbohydrate intake again with the help of maltodextrin (1 x 500ml can per day),
  • Limit the intake of raw fruit and vegetables, because they are rich in fibre and can speed up bowel movements.

D-1: The day before the marathon

  • Increase intake of maltodextrin with 2 x 500ml cans during the day,
  • Drink plenty of fluids throughout the day.

Day of the marathon

The last meal must be effective, rich in carbohydrates and easy to digest (limit fibre and fat). It should be taken 3hrs before the start to ensure it is digested properly
Its main aim is to maximise energy reserves.

Example: Super cake is the ideal food.

During the marathon :


  • Avoid dehydration
  • Avoid hypoglycaemia and the complete exhaustion of energy reserves
  • Compensate for vitamin and mineral losses
  • Avoid digestion problems.


The majority of marathon runners start the race without a flask or water bottle even though it is recommended to drink regularly and right from the start of the race! In any event, you mustn't wait to feel thirsty before drinking. The refreshment stands are therefore very important as they offer cold water. Don't miss them!

Several solutions for avoiding hypoglycaemia:

  • Drinking energy drinks (but this means taking a can for the race),
  • Taking energy gels: easy to take and practical to carry. They need to be consumed with water. Ideally they should be taken before each refreshment break and for the final ¼ of an hour of the race.
  • Eating energy bars: Chewing during the race can be restrictive, so take along products that are easy to chew.

After the marathon:


Compensate for water losses,
Restore vitamin and mineral losses
Restore energy reserves.


It is important to rehydrate as soon as you have crossed the finish line.
If possible, choose a recovery drink that includes carbohydrates, vitamins and minerals, to compensate for losses as a result of the race. Proteins to facilitate muscle recovery.
Following this, make sure you eat some carbohydrates (energy bars, dry fruit, fruit, gingerbread, health food biscuits, etc.)

To avoid digestion problems on the day, during training sessions you should test the products you will be using for the race. Indeed, the type of food ingested during a marathon is a very personal choice.

Marie Fauchille
Dietician | Nutritionist
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